Mahonia japonica ( Oregon grape )

Characteristics

Cultivar:	n/a
Family:	Berberidaceae
Size:	Height: 6 ft. to 6 ft. Width: 10 ft. to 10 ft.
Plant Category:	landscape, shrubs,
Plant Characteristics:	decorative berries or fruit, spreading,
Foliage Characteristics:	evergreen,
Foliage Color:	blue-green to gold, green, red to burgundy,
Flower Characteristics:	fragrant, showy,
Flower Color:	yellows,
Tolerances:	deer, heat & humidity, pollution, rabbits, seashore, slope,

Requirements

Bloomtime Range:	Early Spring to Late Spring
USDA Hardiness Zone:	7 to 8
AHS Heat Zone:	Not defined for this plant
Light Range:	Part Shade to Sun
pH Range:	7.5 to 8.5
Soil Range:	Loam to Clay Loam
Water Range:	Normal to Moist

Plant Care

Fertilizing

How-to : Fertilization for Established Plants

Established plants can benefit from fertilization. Take a visual inventory of your landscape. Trees need to be fertilized every few years. Shrubs and other plants in the landscape can be fertilized yearly. A soil test can determine existing nutrient levels in the soil. If one or more nutrients is low, a specific instead of an all-purpose fertilizer may be required. Fertilizers that are high in N, nitrogen, will promote green leafy growth. Excess nitrogen in the soil can cause excessive vegetative growth on plants at the expense of flower bud development. It is best to avoid fertilizing late in the growing season. Applications made at that time can force lush, vegetative growth that will not have a chance to harden off before the onset of cold weather.

Light

Conditions : Partial Sun, Partial Shade

Part sun or part shade plants prefer light that is filtered. Sunlight, though not direct, is important to them. Often morning sun, because it is not as strong as afternoon sun, can be considered part sun or part shade. If you live in an area that does not get much intense sun, such as the Pacific Northwest, a full sun exposure may be fine. In other areas such as Florida, plant in a location where afternoon shade will be received.

Conditions : Types of Pruning

Types of pruning include: pinching, thinning, shearing and rejuvenating.

Pinching is removing the stem tips of a young plant to promote branching. Doing this avoids the need for more severe pruning later on.

Thinning involves removing whole branches back to the trunk. This may be done to open up the interior of a plant to let more light in and to increase air circulation that can cut down on plant disease. The best way to begin thinning is to begin by removing dead or diseased wood.

Shearing is leveling the surface of a shrub using hand or electric shears. This is done to maintain the desired shape of a hedge or topiary.

Rejuvenating is removal of old branches or the overall reduction of the size of a shrub to restore its original form and size. It is recommended that you do not remove more than one third of a plant at a time. Remember to remove branches from the inside of the plant as well as the outside. When rejuvenating plants with canes, such as nandina, cut back canes at various heights so that plant will have a more natural look.

Watering

Conditions : Normal

Normal is defined as regular watering to a depth of 18 inches, but periodically dries out in the top 7 inches between waterings.

Conditions : Moist and Well Drained

Moist and well drained means exactly what it sounds like. Soil is moist without being soggy because the texture of the soil allows excess moisture to drain away. Most plants like about 1 inch of water per week. Amending your soil with compost will help improve texture and water holding or draining capacity. A 3 inch layer of mulch will help to maintain soil moisture and studies have shown that mulched plants grow faster than non-mulched plants.

Conditions : Outdoor Watering

Plants are almost completely made up of water so it is important to supply them with adequate water to maintain good plant health. Not enough water and roots will wither and the plant will wilt and die. Too much water applied too frequently deprives roots of oxygen leading to plant diseases such as root and stem rots. The type of plant, plant age, light level, soil type and container size all will impact when a plant needs to be watered. Follow these tips to ensure successful watering:

* The key to watering is water deeply and less frequently. When watering, water well, i.e. provide enough water to thoroughly saturate the root ball. With in-ground plants, this means thoroughly soaking the soil until water has penetrated to a depth of 6 to 7 inches (1' being better). With container grown plants, apply enough water to allow water to flow through the drainage holes.

* Try to water plants early in the day or later in the afternoon to conserve water and cut down on plant stress. Do water early enough so that water has had a chance to dry from plant leaves prior to night fall. This is paramount if you have had fungus problems.

* Don't wait to water until plants wilt. Although some plants will recover from this, all plants will die if they wilt too much (when they reach the permanent wilting point).

* Consider water conservation methods such as drip irrigation, mulching, and xeriscaping. Drip systems which slowly drip moisture directly on the root system can be purchased at your local home and garden center. Mulches can significantly cool the root zone and conserve moisture.

* Consider adding water-saving gels to the root zone which will hold a reserve of water for the plant. These can make a world of difference especially under stressful conditions. Be certain to follow label directions for their use.

Conditions : Normal Watering for Outdoor Plants

Normal watering means that soil should be kept evenly moist and watered regularly, as conditions require. Most plants like 1 inch of water a week during the growing season, but take care not to over water. The first two years after a plant is installed, regular watering is important for establishment. The first year is critical. It is better to water once a week and water deeply, than to water frequently for a few minutes.

Planting

How-to : Planting Shrubs

Dig a hole twice the size of the root ball and deep enough to plant at the same level the shrub was in the container. If soil is poor, dig hole even wider and fill with a mixture half original soil and half compost or soil amendment.

Carefully remove shrub from container and gently separate roots. Position in center of hole, best side facing forward. Fill in with original soil or an amended mixture if needed as described above. For larger shrubs, build a water well. Finish by mulching and watering well.

If the plant is balled-and-burlapped, remove fasteners and fold back the top of natural burlap, tucking it down into hole, after you've positioned shrub. Make sure that all burlap is buried so that it won't wick water away from rootball during hot, dry periods. If synthetic burlap, remove if possible. If not possible, cut away or make slits to allow for roots to develop into the new soil. For larger shrubs, build a water well. Finish by mulching and watering well.

If shrub is bare-root, look for a discoloration somewhere near the base; this mark is likely where the soil line was. If soil is too sandy or too clayey, add organic matter. This will help with both drainage and water holding capacity. Fill soil, firming just enough to support shrub. Finish by mulching and watering well.

How-to : Planting Perennials

Determine appropriate perennials for your garden by considering sun and shade through the day, exposure, water requirements, climate, soil makeup, seasonal color desired, and position of other garden plants and trees.

The best times to plant are spring and fall, when soil is workable and out of danger of frost. Fall plantings have the advantage that roots can develop and not have to compete with developing top growth as in the spring. Spring is more desirable for perennials that dislike wet conditions or for colder areas, allowing full establishment before first winter. Planting in summer or winter is not advisable for most plants, unless planting a more established sized plant.

To plant container-grown plants: Prepare planting holes with appropriate depth and space between. Water the plant thoroughly and let the excess water drain before carefully removing from the container. Carefully loosen the root ball and place the plant in the hole, working soil around the roots as you fill. If the plant is extremely root bound, separate roots with fingers. A few slits made with a pocket knife are okay, but should be kept to a minimum. Continue filling in soil and water thoroughly, protecting from direct sun until stable.

To plant bare-root plants: Plant as soon as possible after purchase. Prepare suitable planting holes, spread roots and work soil among roots as you fill in. Water well and protect from direct sun until stable.

To plant seedlings: A number of perennials produce self-sown seedlings that can be transplanted. You may also start your own seedling bed for transplanting. Prepare suitable planting holes, spacing appropriately for plant development. Gently lift the seedling and as much surrounding soil as possible with your garden trowel, and replant it immediately, firming soil with fingertips and water well. Shade from direct sun and water regularly until stable.

Problems

Pest : Whiteflies

Whiteflies are small, winged insects that look like tiny moths, which attack many types of plants. The flying adult stage prefers the underside of leaves to feed and breed. Whiteflies can multiply quickly as a female can lay up to 500 eggs in a life span of 2 months. If a plant is infested with whiteflies, you will see a cloud of fleeing insects when the plant is disturbed. Whiteflies can weaken a plant, eventually leading to plant death if they are not checked. They can transmit many harmful plant viruses. They also produce a sweet substance called honeydew (coveted by ants) which can lead to an unattractive black surface fungal growth called sooty mold.

Possible controls: keep weeds down; use screening in windows to keep them out; remove infested plants away from non-infested plants; use a reflective mulch (aluminum foil) under plants (this repels whiteflies); trap with yellow sticky cards, apply labeled pesticides; encourage natural enemies such as parasitic wasps in the garden; and sometimes a good steady shower of water will wash them off the plant.

Fungi : Leaf Spots

Leaf spots are caused by fungi or bacteria. Brown or black spots and patches may be either ragged or circular, with a water soaked or yellow-edged appearance. Insects, rain, dirty garden tools, or even people can help its spread.

Prevention and Control: Remove infected leaves when the plant is dry. Leaves that collect around the base of the plant should be raked up and disposed of. Avoid overhead irrigation if possible; water should be directed at soil level. For fungal leaf spots, use a recommended fungicide according to label directions.

Pest : Scale Insects

Scales are insects, related to mealy bugs, that can be a problem on a wide variety of plants - indoor and outdoor. Young scales crawl until they find a good feeding site. The adult females then lose their legs and remain on a spot protected by its hard shell layer. They appear as bumps, often on the lower sides of leaves. They have piercing mouth parts that suck the sap out of plant tissue. Scales can weaken a plant leading to yellow foliage and leaf drop. They also produce a sweet substance called honeydew (coveted by ants) which can lead to an unattractive black surface fungal growth called sooty mold.

Prevention and Control: Once established they are hard to control. Isolate infested plants away from those that are not infested. Consult your local garden center professional or Cooperative Extension office in your county for a legal recommendation regarding their control. Encourage natural enemies such as parasitic wasps in the garden.

Miscellaneous

Conditions : Deer Tolerant

There are no plants that are 100% deer resistant, but many that are deer tolerant. There are plants that deer prefer over others. You will find that what deer will or will not eat varies in different parts of the country. A lot of it has to do with how hungry they are. Most deer will sample everything at least once, decide if they like it or not and return if favorable. A fence is the good deer barrier. You may go for a really tall one (7 to 8 feet), or try 2 parallel fences, (4 to 5 feet apart). Use a wire mesh fence rather than board, since deer are capable of wiggling through a 12 inch space.

Conditions : Pollution Tolerant

Air pollution is becoming a bigger problem each day. Pollutants in our air damage plants. The plants are damaged by absorbing sulfur dioxide, ozone, peroxyacetyl nitrate, ethylene, and nitrogen dioxide through their pores. Cell membrane damage may result in leaf drop, blotched or burnt looking leaves, or off-colored tissue between veins. Vehicles and industrial processes are the key culprits and conditions worsen on hot summer days. Though planting only pollution tolerant plants is not the solution to this problem, it is a visual band aid. Your Cooperative Extension Service may have a list of plants that are more pollution tolerant in your area.

Conditions : Rabbit Tolerant

As cute as they are, rabbits can really damage a vegetable garden. Young, tender lettuce plants seem to be their favorite. If a free-roaming dog is not a possibility for you, consider installing raised vegetable beds and covering tender shoots with netting. If you have ample room, you can opt to plant enough for you and the bunnies. Scents don't always repel animals, as they get used to them and are often washed off in the rain.

Conditions : Slope Tolerant

Slope tolerant plants are those that have a fibrous root system and are often plants that prefer good soil drainage. These plants assist in erosion control by stabilizing/holding the soil on slopes intact.

Glossary : Border Plant

A border plant is one which looks especially nice when used next to other plants in a border. Borders are different from hedges in that they are not clipped. Borders are loose and billowy, often dotted with deciduous flowering shrubs. For best effect, mass smaller plants in groups of 3, 5, 7, or 9. Larger plants may stand alone, or if room permits, group several layers of plants for a dramatic impact. Borders are nice because they define property lines and can screen out bad views and offer seasonal color. Many gardeners use the border to add year round color and interest to the garden.

Conditions : Erosion Control

Plants that help to control erosion have fibrous root systems that help to keep soil intact. Leaves and the overall form of a plant can prevent erosion by breaking up water droplets before they hit the ground, lessening splashing and runoff.

Conditions : Fall Color

Fall color is the result of trees or shrubs changing colors according to complex chemical formulas present in their leaves. Depending on how much iron, magnesium, phosphorus, or sodium is in the plant, and the acidity of the chemicals in the leaves, leaves might turn amber, gold, red, orange or just fade from green to brown. Scarlet oaks, red maples and sumacs, for instance, have a slightly acidic sap, which causes the leaves to turn bright red. The leaves of some varieties of ash, growing in areas where limestone is present, will turn a regal purplish-blue.

Although many people believe that cooler temperatures are responsible for the color change, the weather has nothing to do with it at all. As the days grow shorter and the nights longer, a chemical clock inside the trees starts up, releasing a hormone which restricts the flow of sap to each leaf. As fall progresses, the sap flow slows and chlorophyll, the chemical that gives the leaves their green color in the spring and summer, disappears. The residual sap becomes more concentrated as it dries, creating the colors of fall.

Glossary : Evergreen

Evergreen refers to plants that hold onto their leaves or needles for more than one growing season, shedding them over time. Some plants such as live oaks are evergreen, but commonly shed the majority of their older leaves around the end of January.

Glossary : Shrub

Shrub: is a deciduous or evergreen woody perennial that has multiple branches that form near its base.

Glossary : Fragrant

Fragrant: having fragrance.

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